1. Field of the Invention
The present invention relates to an eye detection apparatus provided in, for example, a head mount display to be mounted on the head of a user, for detecting the position of a pupil of the user.
2. Description of Related Art
When an observer wears a head mounted display (which will be abbreviated as HMD hereinafter) and observes an image, if the designed optical axis of the display optical system and the direction of the line of sight of the observer do not coincide with each other, there is a possibility that when the observer moves his/her eye to observe a peripheral portion of the image, the eye deviates from the pupil diameter of the display optical system to cause eclipse or spoil strength of observed images, though it is possible to observe the central portion of the image.
To make the HMD suitable for an increased number of observers, it is necessary to make the pupil diameter of the display optical system larger. However, the size of the display optical system will increase with the increase in the pupil diameter.
There are technologies for detecting the position of a pupil or the direction of the line of sight of an observer, such as a technology in which an eye is irradiated with several infrared rays (IR) and the direction of the line of sight is detected based on the reflected rays and Purkinje images (see, for example, Japanese Patent Application Laid-Open No. H05-66340, Japanese Patent Application Laid-Open No. H06-276459 and Japanese Patent Application Laid-Open No. 2001-142026).
In this method, it is required that the reflected IR rays to be detected be within the area of the colored part of the eye, and it is necessary that the position of the eye of the observer be in a limited small area (a predetermined area) relative to the HMD. In connection with detecting the direction of the line of sight, to detect Purkinje images, it is necessary to move the eye to left and right over an angle range of about 15 degrees.
However, the observer does not necessarily always wear the HMD in the same position. In addition, when the observer wears the HMD, the position of an eye of the observer relative to the HMD is not always in the aforementioned predetermined area. In cases where the position of the eye is not in the predetermined area, the position of the pupil of the observer cannot be detected accurately using the aforementioned conventional detecting method.
Moreover, while there is a trend of widening the angle of field of the HMD recently, the above-described conventional detection method cannot cope with the widening of the angle of view, since its detection area is limited.